Ive only seen a few episodes fully and a load of highlights off youTube but from those here are my favourites:

10: T-minus Vs Sunshine lollibot (We said flip, T-minus said how high)
9: Turbo Vs ??? (The real Phrisbee goes flying)
8: Surgeon General Vs Frostbite (I bet you could build a robot out of the parts that went flying)
7: T-minus Vs Heavy metal noise (We all knew that something was going to fly, weather it was a robot or a bucket of parts was the question)
6: Backlash Vs Disposable hero (Blink and you miss total destruction)
5: Final destiny Vs The swarm (the physical meaning of being slapped around the battlebox)
4: Toro Vs New Cruelty (If you stand near this SHW you get the idea of the pure power Toro produces per flip)
3: Ziggo Vs Scrap daddy (Scrap by name, scrap by nature)
2: Nightmere Vs Slam job (Two words, BIG HIT)
1: Ziggo Vs Missing link (My first fight and probably one of the best.)

Some of these may be arguable but they were the first BB fights I saw (Monday, 8:00, BBC 2, March 2000.) and those fights I remember best (How many people think that Nemesis Vs Roadblock was one of their favourite fights.)