Both the Poker and V60 are a standard fit in aftermarket cases. The Poker is very heavy and some love this and some don't- because of the aluminum case. The Poker also comes with quality keycaps- PBT or ABS, depending on the model you buy, but these caps are generally superior to the V60's ABS.
The Poker is able to reprogram keys if you would like to move them. The V60 can be had for about 20-40 us dollars less than the Poker 3, depending on which models you are looking at. The V60 does have some nice color schemes to choose from which is a very nice touch. I like them both. Depending on what you are looking to replace or customize, some of this may be helpful or not at all.
Which switch to choose is a different story. This is very personal and everybody has their own opinion. Blue is my least favorite EVER, but some live for it. My preference is Cherry Brown, which many may dislike. There are a thousand postings and websites offering details as well as heated debates on this topic.