Nvidia - only a GTX1050 for now. But maybe be investing in a small rig (2 or 3 GPU's with reasonable hashing power).
Run the Nicehash profitability test and see what algo brings the most profit. Then look for coins that can be mined with this algorithm 
.The Nicehash calculator is useful, but Nicehash itself as a miner is not very useful because of the very high payout threshold in Bitcoin(last time on the website that was nearly $100 worth - which would take weeks to mine).