As above.
TiA for recommendations
DS
For carrying or for workshop?
Sorry - I should have said "best chain splitter for taking out riding."
Oops!
I have a Park one that I carry with me. In fact I used it to help out a guy at Cannock on Saturday who had broken his rear mech
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Had one of these in my back pack for years , it's never let me down yet. bought for about £3.99 at those 1 day sale things(cycle promotions)
toppeak multi tool ftw
"This award winning bike tool is consistently reviewed as the editors choice throughout the cycling industry. With 13 of the most useful tools for bike repair in one package, the Cool Tool is the essential bike tool for professionals and beginners alike. The Cool Tool features an adjustable head wrench (opens to 19mm), an emergency tire lever, a chain tool, Allen wrenches (sizes 4-5-6-8-10 mm), 14 & 15 mm sockets, cross head screwdriver, spoke wrench, and a bottle opener."
= Gerber Cool Tool - best chain tool for EVERY speed !
For taking on a ride - the one on my topeak alien multitool. Its a good chaintool in any circumstances. Its the only tool I carry and the only tool I have ever needed. Anything else is redundant weight.
WTF do you need an adjustable spanner for as above?
The one in my Topeak Hexus is better than my Lezyne workshop one. This is actually quite annoying 
Certainly no need for a seperate one.
Park CT-5 "mini brute"
actually use one in the workshop every day, and replace the replaceable pin every few months (normally if I bend it braking a heavily corroded or damaged chain), but its excellent value / quality and has survived bike workshop abuse/...
CT5 seconded. We have them in our workshop and I carry one in my out&about kit too, never failed me yet.
(additional tip: take off the original arm and use a torx key (one of the ones supplied with Avid brakes) instead, it saves about 3g!)