Not Geka-pattern (fire hose derivative) brass quick-coupling hose fittings, as used by professional nurseries etc - very liable to drip-leakage - kept losing whole tankfuls of rainwater till I realised, now turned off at source when not distributing. Great selectioin of quality fittings tho.

I use a timer on my irrigation system only turns on to do watering then off again, bring timer indoors in winter

I've always found the ordinary plastic Hozelock adaptor for a threaded tap outlet works perfectly well. There's a rubber sealing washing at the bottom of the female plastic bit - if the brass tap won't screw in far enough to squeeze the washer then add another washer or cut down the end of the tap.
Put it all together with Red Hermetite.

Taps that leak up the spindle are a pet hate of mine. Usually you can fix them in minutes by winding a few inches of string set in grease into the space and then screwing down the gland nut again.

Ball valve tap? I don't recall ever having one leak. My current hose pipe tap is actually a gas ball valve; good for 8 years now. Sympathise with the challenges on hozelock and it's copies- one of the few things where I tend to buy the leading brand name because it seems quality control of the copies is quite variable/loose or tight fit, poor hose grippers, locking collars that pop off easily.. You could also consider using blue MDPE water supply pipe and fittings - https://www.drainageshop.co.uk/20mm-fittings.html - if you need to drip irrigate just get a 1mm drill out and hole the pipe. For regulating flow, have a screw tap in line with a ball tap; the ball is the on off you use all the time, the screw you set and leave so your 1mm holes aren't jetwashing your rhubarb :)

Second cliff's comments about verifying sealing washers etc; I've a few cheap irrigation systems from eBay (7 quid for 23m of pipe and a bag of little T and disc fittings that drip) and sealing them at the tap end was a bit of a nuisance as it was a hard plastic:plastic seal on the mesh filter. I cut up an old bicycle inner tube into rubber washers in the end