this is like asking what are the best number to pick to win the lottery
its impossible to suggest a used machine for you,
we have no clue what your needs are for it, , what size machine, , wheels, or tracks?
how new or old?
can you do repairs, and or fix things yourself? what is your skill set on doing repairs/
next is, there is No BEST model machine that last forever , is problem free and or holds its value better than other models!
wanting to buy something, use it for a yr and sell it for what you paid for it,??
is asking a lot!
as hours added to any machine lowers its value,, as does wear and tear!
using a machine adds wear to pin's bushings and buckets and hoses , tires, tracks,and so on!
its impossible to not have wear and tear if you use it
and even age alone lowers values!, as hoses dry out over time and can crack and need to be replaced and they are not cheap to replace, and many are time consuming to get off and re install, requiring skills to do so! plus older machines can be harder to find parts, as pending how old, many are no longer even made!
so, wear and tear and AGE can cost $$$ and lower values of things! just no way around it!
unless you happen to BUY a machine at less than its really worth and then your ahead of the game, but few folks sell things for less than they are worth!
what you BEST option might be, is to find the best condition used machine that fits your needs, that has local support(as in brand dealer near by)
and from there use with care, do PM's as needed and not abuse it, and when done, look up market value and try and get that for it!
if you do NOT know what to look for on used machines, I highly suggest taking someone with you that does when you go look at possible machines! it can save you a lot of $$ , as sadly many sellers today are scammers, and will not tell you the real history of a machine, or maybe even know it, and will want money over being honest!, its a sad world were in these days ,
buyer beware has never been higher risk!