I like the concept behind base mods, definitely. But I'll admit that some leg and arm mods take some time to grow on me. I'm more open, in general, to leg mods in that I like most leg mods immediately. But it's easy for the angle to completely throw off the center of gravity on the avatar and make them look like they're tipping forward or backward. And I hate that. The thorn heels in Rosamund's Revenge immediately come to mind as a culprit.
I initially hated that mod because the placement of the straight leg makes your avatar look weirdly tilted forward. I've found that you can disguise it sometimes, depending on what you pair the leg mod with, so it's grown on me and I find myself using it far more than I thought I would. There are a lot of other leg mods I thought I'd never use for similar reasons, that eventually I found a use for. There are some leg mods I think I will always hate, though.
Arm mods, to me, are an entirely different animal. I hate about 95% of the arm mods we get. First of all, I understand why they have to be 'gloved' so they can be used with all skin tones. But most of the time the sleeve-glove thing they have going on just looks really weird to me. Secondly, I don't know if tiny arms are just really hard to pixel but most arm mods look oddly thin and noodly to me. The other difference between arm and leg mods that really kills the whole arm mod thing for me is that--when you move your legs, it's pretty easy to avoid repositioning other body parts to compensate for the leg position. But when you move your arms, because all the muscles are connected, it tends to impact torso, neck and head placement. Arm mods on our avatars only reposition the arms though--and since we don't really have necks to speak of, this can make the shoulder area look incredibly awkward. I realize that this is a limitation of the avatar base and not that the artists suck or anything. But it contributes to why I'm super picky about arm mods.
I also think it's very easy to make the arms too long and the hands freakishly large and clownish. For some reason, making awesome legs seems to be much easier for the artists than making awesome arms. But that just means when we do get an awesome arm mod, I'm really happy about it.
I'm okay with skins but I don't like the potions because I change my avatar far too often, and get bored with them. So I like skins that are part of items, so I can switch them out frequently.