Mb is on my to buy list for sure, votk looks dope, dominion I dunno it seems fun but the theme seems fairly bland. I'd want to play dominion before I paid for it.
If Millennium Blades ($60 USD on Amazon right now) is a hit, definitely grab the Set Rotation expansion ($30-ish USD).
As for Dominion, that's a fair complaint. It has a standard medieval fantasy theme, but it is a classic for a reason. Here's what I'd suggest:
1. Try to find a local board game store that has a playtest / playing area. They should have a copy of Dominion and you can try it out.
2. What is the draw of Magic for you and your friends? If what you love is carefully constructing an optimal deck from a full range of choices, Dominion does provide that, a sort of competitive optimization given a specific list of cards to choose from. If what you love instead is a strong theme and flavor text, avoid Dominion.
3. What is your budget? Millennium Blades has a ton of content but is going to run $60-ish (or $90 with Set Rotation). Dominion is going to run $30-ish + $30-ish per expansion (don't buy any expansions until trying the game). Valley of the Kings is going to run $20, or $50 for the base game plus BOTH expansions.
I haven't played some of the other suggestions like Mage Wars Academy, but they are probably good choices. If you simply want to try deckbuilding mechanics with decent theme, dropping $20 on Valley of the Kings (or even $14 for the standalone Afterlife expansion, since you can buy them out of order and then mix/match) is by far the most compact and lowest risk way to experiment.
If you only get one shot on selling them on other card games, and if you fail they will forever play only Magic, and they have a sense of humor, I think Millennium Blades is the way to go -- but try simulating a game by yourself first so you understand the rules, otherwise you may turn people off by being too slow.