7210, or 5100, or 3100 or 6100

hey everyone. i just need help in deciding which phone is better. i dont mean feature wise. just need a phone thats very reliable and doesn't drop out on calls and stuff. basically which one u's reckon is reliable and is durable. 7210, 5100, 6100, or 3100 __________________ well its ur network that decides whether 2 give u service not the fone wat u have r 4 very different fones 7210 very good looking and very reliable 3100 cheap reliable fone 5100 a fone for sum1 who is always dropping fones,lol 6100 again very nice looking and very small