as earlier you say best is 40mhz.
The best on paper is 2.4Ghz, unfortunately these sets are very expensive, my Spektrum DX-6i cost £110 just for Tx and Rx, no battery packs or servos or anything else included. I also have a DX-3 that came with Rx, nicads, two servos and a switch for £130.
To give you an idea of 40Mhz gear cost, Howes Models in Oxford will sell you a Futaba Skysport 4 for £100 with gear, £40 without, or a Futaba 4EX computer radio for £115 with gear, £45 without, or a Futaba 2ER for £38 with gear, £8.99 without (this one only needs duracells too).
I dont have shares in Futaba or anything, as it may seem, but Futaba gear is by far the best (watch the rows start...). Ask anyone at my glider club at Ivinghoe Beacon and they will tell you this is true. So I suspect will people at Stevenage boat club.
I would advise 2.4 gig stuff, as I love it (despite what everyone else says) , but it is quite expensive.
Andy