I would say..... McCracken Booth Woodhall Tibbs Coldwell/Nelson McCracken always seems to give sound advice in-between rounds from what I've heard. He's not one of these cheerleaders than most British trainers seem to be. He actually gives his fighter excellent instructions. Booth is a bit unconventional in the way he accesses Boxing but I can decipher what he's trying to say most the time and its usually good/decent advice. Atleast Booth is someone who thinks outside of the box and is open to different ideas/methods. I've been in Woodhall's gym and on the pads with him and listened to him so I know he knows his Boxing. Jimmy Tibbs is an old school respectable British trainer imo. I like Coldwell because he tries to get all his fighters fighting the right way, trying to box, move, and not get hit. Nelson has had some good recent results which you cant argue with. He's managed to get the best out of Burns, and Simpson's victory over Lindsay cannot be ignored either. He might be a competent trainer more than a top top trainer though imo. Biggest criticism I would have of Nelson is that he comes across like he knows it all, and I'm skeptical of any trainer like that, cause to keep learning and improving you have to be more open minded imo. Usually people who think they know stuff dont.
In no paticular order... Booth Farnell Ingle Tibbs Gallagher Honourable mention to Billy Nelson and Dave Coldwell