I like both Thorpe Park's and Alton Towers' entrances. Both are great:
At Thorpe Park, you walk across the bridge onto what seems an island, and you're lead into "Port Atlantis" (the dome) which is themed inside as an underwater port, and then as you step out of the dome you see the whole park set out right in front of you. You've got the beach and Tidal Wave on your right with the ruined buildings and Nemesis Inferno peering over the top. Right in front you have a large pyramid with Colossus' cobra roll standing tall, and every so often you see Slammer pop up behind X:. And then to your left you see Vortex swinging and spinning with Zodiac popping up in the background and Quantum doing its thing behind the bushes.
I could go on really, you know what I mean. It seems like a huge adventure playground sitting there waiting for you.
On the other hand, you have Alton Towers with everything hidden, waiting for you to discover it (okay, Spinball Whizzer is an exception unfortunately). You walk down Towers Street and you have the Alton Towers in front of you in the mist with the lake in front. There's not a lot I can say, this alone is enough to create an amazing entrance!
Both parks have a totally different atmosphere. Seeing as Thorpe is my local park, I'm gonna side with that :lol: Thorpe seems to have an intense and nervy atmosphere, especially in the Lost City (no, not because of the chavs!) as well as the cheesy atmosphere in Amity Cove which Alton now has in Ugland, but I think Alton is the more magical of the two with the towers. And obviously, there are areas of boths parks which I think don't have an atmosphere at all. X Sector and the Inferno end of Calypso Quay.
One thing I think Thorpe have over Alton is the ride music. Every single ride has its own sound track, even the old Rocky Express :lol: I find at Alton only the major rides have music, and the volume isn't loud enough (but we all know why that is :roll: ) but take a walk over the bridges of Colossus and you hear the amazing orchestral music all around you (which unfortunately leaks into Canada Creek now that Slammer has been built - Dolly Parton music has dissapeared here ) :(
Obviously my post is slightly biased because I've been going to Thorpe Park since I was 4, and I've only been to Alton 9 times, but here's what I think :D