Silicone is my favorite. Glass is very long lived though. Metal is also. I have one plastic clit vibe that i like, Lelo Mia. Otherwise i'm silicone and glass all the way. I'll eventually try metal and wood but I have to save points and pennies for those!
I like every safe material I've tried and I suppose I will like the ones I haven't, when I get the chance. Cheap plastic feels great on my clit, glass can firmly stimulate my g-spot (suppose the same would be true of metal and wood) and silicone has a bit of give that makes penetration feel wonderful.
I haven't picked hard plastic in the survey because you said long term and I tend to drop hard plastic vibes and they crack around the base. I'm more careful with glass. I've also observed some discoloration on my PU coated vibe. Bleaching it only makes it worse.
I hate jelly and anything porous, and I especially hate latex. Yuck! I'm just obsessed with glass right now and 3/4 of my collection are glass dildos. I've never tried firm plastic but I reckon I may like it, I just try to go for 10's on the safety scale!
Silicone is my absolute favorite. I like glass as a material, but I've currently only got one glass toy (I had a few others, but it turns out that some shapes aren't a good idea while my pre-orgasmic muscle spasms are happening). I also like plastic, but I don't think it could be considered a good "long term" material, generally speaking (though I have actually gotten a number of years out of a few plastic toys).
The majority of my toys are silicone. I have 3 glass toys that I like and plan on adding more to my collection. My next purchase is going to be the Njoy pure wand and it will be my first steel product so I don't know I'll like it, but I'm giving it a shot. I'm finally moving out of my silicone zone after being here for a while.