Hm, I can never decide on my favourite flat ride. I've got a soft-spot for Rush, it's got a great sense of speed and on the one swing you get some brilliant air-time, but on the other you get some gentle floaty airtime. Then you have Maelstrom, which gives a more intense and exciting ride, I absolutely love Maelstrom, if anything it's the main reason (apart from Apocalypse) I visit Drayton Manor.
Bling doesn't do much for me, I consider it the tamest of the flat rides I've been on, you get some good height but compared to compact Top Scan models Bling pales in overall intensity. I found myself resting my head against the restraints, it can be fun, but hardly thrilling.
Ripsaw is commonly slated, but I find it a great flat ride. It might just be because of the park, it's a great break from all of the coaster-whoring around Alton and when it wants, can be quite a headrush.
Enterprise's are utter turd, and so is Submission.
Oh did I forget to mention Venom at WMSP, that is without a doubt THE BEST DROP TOWER IN THE COUNTRY! :--D
Cliffhanger's definitely my favourite tower ride by a long way. Powerful, plenty of airtime and a decent length cycle, which is the only thing I don't like about its main rival, Ice Blast.
I couldn't really pick a single ride as a favourite spin/swing ride. It would have to be between Rush, Maelstrom and Flip Flop. Rush is a great ride (I love the acceleration and the airtime), but it's just got such a short cycle. As soon as you've started really getting into it, it finishes. Maelstrom/Flip Flop are just plain fun.
An honourable mention also to Lightwater Valley's temporary (and sadly late) Topscan, Whirlwind. A proper Topscan on a brilliant ride cycle. It was a great addition to the park for the few months it was there, even if it looked horrid and randomly placed there.
Only have been to two UK parks: Alton and Thorpe. But out of those two I would choose Slammer and Samurai. Slammer the slightly better ride but both are great! The rest of the flats I rode in the UK were pretty dull..