With such a plethora of online slots out there, finding the best online casinos to play them at can be a bit of a chore. So, being pretty well versed in this sort of thing, the following list of online casinos are the ones I would recommend players from the UK and Europe.

• Spin Palace (Microgaming Software) - As I write, they have an excellent freeplay slots promotion where you get a bankroll and an hour to play all your slots with a chance to win up to £200. Over 140 slots to choose from.
• Roxy Palace (Microgaming) - Not the quickest online casino to pay out, but definately the best ongoing loyalty bonuses if you stick around. As a VIP, I often receive 2 or 3 bonuses every week of varying amounts. 
• 32Red (Microgaming) - My personal favourite online casino. Another that rewards loyal players more than newbies but excellent slots again and excellent support. Also run the very popular slot tournaments on “Tombraider” and “Thunderstruck“
• All Jackpots (Microgaming) - Accepts USA players too and runs the slot tournaments as above. Good reputation but better for US players by all accounts.
• Virgin Casino (Wagerworks) - One of two casinos where I play the excellent Cleopatra slot. Light on good slots but being Flash, it’s instant and quick and very fast to pay cashouts.
• Blue Square (Wagerworks) - Online casino similar to Virgin, but slightly better loyalty rewards for slots players.
• Club USA (RTG) - A good casino to try the very entertaining if a little tight RTG Real Series slots. Despite the name, takes players from all countries. Offers loads of bonuses but with tight retsrictions.
• iNetBet (RTG) - As Club USA - not as many bonuses as Club USA (above) but less restrictions generally.
• Gaming Club UK (Microgaming) - Part of a big online casino group so expect slower support, but does have some very good slots promotions if you stick around - win cars and stuff!
• Challenge (Microgaming) - A Casino Action group casino. Great slots and truly instant Neteller cashouts, albeit with certain restrictions. A big signup bonus but requires 3 deposits.
• UK Casino Club (Microgaming) - Another strong casino from Casino Action with lots of slots and slot competitions, plus instant Neteller payouts once again.