There are basically 3 loadouts I use about 95% of the time and it depends on whether we're kiting or camping. I personally love playing medic. It's basically a sort of mini-game everytime I play it as I try to deal as much damage possible to the specimens as I can while trying to keep everyone alive. Assume I'm talking about HoE medic unless otherwise stated.
Axe/LAR/MP7M for kiting is obvious in my view. Basically the ability to take on anything possible without much effort, though you might need a friend if you want to take on scrakes. Backhits on a scrake's head will stun them. Kite FPs around by alt firing the axe 2 times successively rather than 1 time as a berserker. LAR for crawlers, husks, sirens. The best all-around loadout I feel.
Machete/DHC/LAR/MP7M for camping. LAR is for generalized killing. DHC is for grabbing attention. Fairly standard I feel.
Machete/Crossbow/MP7M for a more specialized role. You're to take out sirens and husks so your sharpshooter can save ammo. Fairly simple. Of course, do not shoot at scrakes, you'll just make them rage as you cannot stun them. Do not shoot at FPs unless someone else rages them first. You do terrible damage with the crossbow on FPs unperked.
Now for a "fun" loadout.
Katana/M14EBR/MP7M I'd use more for kiting though I guess you could use it for camping. Just for fun. I feel the Axe/LAR/MP7M is better in almost every way, but you do a great job killing lower tier specimens as the headshot bonus to the M14EBR is huge and will actually kill them off instead of decapping them as would happen if you take, for example, a Scar, a similar weapon. Need 3 hits to kill husks and sirens though. I've used it with success before. Just note the M14 has huge, huge recoil unperked.
Now for some of my thoughts on weapons a medic could use. I won't be factoring in money as logically you would spec into the different perks first to get the weapons on the cheap. There's plenty of money on HoE to get everything offperk even.
Handcannon: Quite useful when camping if specimens come down corridors. Very powerful, great ironsights, will decap many specimens at once. If on suicidal and below, it can replace the LAR since you can body shot crawlers to kill them on those difficulties.
Dual Handcannons: Do not use this to actually kill things. If you are going to use handcannons to actively shoot at things, use the single. Difficult to aim long distance with dualies and they have a very long reload time. use only in a tight situation or to bodyblock/take aggression off a squishier teammate.
Dual 9mm: No.
Lever Action Rifle: The first weapon a medic should get upon entering suicidal and below. You get 200 dosh on suicidal and more on lower difficulties so you have just enough to grab this. On HoE, should grab it as soon as possible as well. I consider this weapon the best offperk weapon available as it allows you to deal with everything short of a scrake or FP quite easily, and it will actually kill and not merely decap. Ability to interrupt reloads is also quite good.
Crossbow: Great for a supportive role as said earlier. Use it to kill a large row of enemies, in particular crawlers, and husks and sirens. Do not try it on scrakes. FPs only when they're raged already.
M14EBR: Decent choice, but not the best. Allows you to solo scrakes. If you have a katana, for example, alongside it, you can solo everything since you will eventually run out of ammo if you only used this. Does require you to be good at aiming with it.
Axe: Great weapon. I would actually recommend taking this over the katana even if you have a berserker to buy you a katana or you had the 1000 dosh for one. The axe is slower, but the difference is that it will kill many things rather than decap. Bodyshots will also kill things in one hit where it would not when using a katana. It will allow you to deal with scrakes if you have a teammate. It will kill FPs faster than a katana.
Katana: As said, I'd recommend an axe instead of this, though if your loadout doesn't have enough space for an axe, the katana will certainly work. It certainly hits faster, which is a definite plus.
Flamethrower: This is an absolutely terrible weapon. You will kill absolutely nothing. You will blind everybody. Never take this weapon, ever.
Mac10: I understand some people like this weapon. I personally don't see the point of it when you can have DHC. The Mac10 is basically an automatic 9mm in terms of power so it's difficult to kill things with it if you are going to use it to kill things. If you're using it to grab aggro, just use DHC since it actually does do decent damage. Plus, it's very similar to the MP7M, so, again, I do not understand the point of using it when there are better options.
M79: Almost never get this. An unperked m79 is pretty terrible and it blind your teammates. If you are someone who constantly blinds your teammates, you're better off standing there doing nothing. You don't even need to heal. You're just better off doing nothing rather than using the m79. This is only in a camping situation. If you're kiting with a large open area, or if you're camping in a spot with a large open area, this changes things. This is usable on crawlers as well as stunning lower level specimens if a teammate is becoming surrounded. On lower difficulties, the M79 does indeed become quite usable since it will actually kill things rather than merely stun them and blind your team. Still, try not to blind your teammates too much.
M32: Toss a few grenades, aim at FP's head/chest, watch FP die. Certainly usable, but if you're the one that needs to take care of FPs, perhaps one of your teammates need to change perks or you should just go demo yourself while taking along an mp7m.
LAW: I don't know what you're thinking.
Bullpup: Not enough damage.
AK: It's okay, but I'd rather have a LAR if I'm going to get a 6 slot ranged weapon since the LAR can take on husks whereas the AK has a bit more difficulty with that.
SCAR: Decent choice. Will decap lower tier specimens with one hit. Has great sights and ammo count. Should use on single shot mode.
Shotgun: Not enough damage nor penetration.
AA12: Possible, but not enough power nor ammo in the hands of a medic. There are better options.
Hunting Shotgun: Absolutely terrible choice. Watch as you kill absolutely nothing with it. Well, I guess you would kill that single clot as an army of gorefasts charge in on you. One of the greatest abilities of the hunting shotgun when a support uses it is it absolutely demolishes an entire hallway of specimens. When you use it offperk on HoE, it'll kill only one or two enemies. The only redeeming factor is you can use it as one of the ways to take on a scrake when you have no armor. Needs a katana alongside it though. Still, should not carry it. Just drop it somewhere in case you need to take care of scrakes alone.
MP7M: Should carry it in your loadout. Your job is primarily to heal. This allows you to heal while far away. So you can potentially help kill things on one side while still able to heal your group on the other side without walking a long distance. Also makes a decent backup weapon. Shouldn't use it primarily though. Very weak, huge recoil, and a long reload time means very few kills and a time when you can't heal.