Not sure whether they're the best but Olivers or Chianti.
Fibre stem so that you can hold back whilst the bait gradually falls through the water to cock the float. Using a very light float, .1g (depth and wind allowing) you can pick up any early intercepts.
However, I also like a wire stem such as the Frostie to cock the float early which is useful if fishing through the water at lower depths (fast drop then slow fall)
Having said that you can get most patterns to perform how you want with the correct shot arrangement and bearing in mind the size of fish and how confident they are feeding. Except perhaps a round body float, probably too buoyant for example. Though even here it is still doable with most of the bulk up the line so that you are just fishing on the bristle. But I digress.
Drennan AS3. Slim, carbon stem. On Sunday I used these to fish mag through the last couple of foot, 4 x nr 11 droppers, most bites were hold ups, showed them clearly. I used to fish wire stems for through the water but I feel with a carbon stem the float is cocked for how much shot you've got down, as opposed to with a wire that cocks straight away.
See what the likes of Andy G, Merce, and other very good roach anglers say - I'm just a novice, but these work for me personally.
Chianti every time for roach shallow. The As3's are good but the important bit of the chainti is the cane bristle. It's bouyant which means it encourages self hooking and leads to many more bites that are hit rather than missed, especially if you use a bulk when they are really having it. Also, carbon stem every time for shallow. Don't tent to break Chiantis when roach fishing.
I find the Preston pt series 3 spot on for following every shot on a strung rig. work well with a loose bulk and droppers just as well too. excellent for all maggot baits. for something bigger like caster I use MB London canal specials mick makes these with a carbon stem for me and not the normal wire. a brilliant float when there is a skim on or tow. I find this works best with a loose bulk set half depth and strung shotting below. I have these from 3x8 all way up to a gram. a good float for searching on the drop from half depth down