3.6GHz quad-core Intel Core i7, Turbo Boost up to 4.2GHz
16GB 2400MHz DDR4
1TB Fusion Drive
Radeon Pro 560 with 4GB video memory
now i dont have room for the 27 inch at all, so i am stuck with the 21.5 one but the thing is that i do plan on doing some gaming on it and i know mac are not made for gaming but i just never had a mac and been wanting one for a while and do plan on using bootcamp for like overwatch and some other games but if i was to get this imac with these spec are they going to last me for a while?
The only change I would recommend to your configuration is to select the 2 TB Fusion Drive. Not because of the extra space but because it comes with a larger SSD partition.
I think fusion drives configured with dual-partitions use pure HDD for the second partition. If you are OK with bootcamp on 5400rpm then go for it - otherwise I'd suggest investing in a large SSD drive.
Funny timing--just last week I returned a custom order 21.5 for a yellow blotch on the screen. Lucky timing. Now, with the changes, the 21.5 with 16G and 1TB SSD is $100 less than the top 27" with 16G and the stock 2TB Fusion. Not quite sure which I will order.