Hi John
Most AGM batterys are a good upgrade over the old Lead acid type, Motobatt were good but their quality is some what suspect now, I had some that were still going strong after 5 years and a couple that failed in under 2 years
The bike shop i use for MOT’s has stopped selling them and now only sell BS brand batterys, have one on my Fireblade and is good
I have an Exide AGM on one RC from M&P and a Motobatt on the other RC, is 3 years old now and still ok, and a cheap eBay AGM on my CB1100F which works ok
One thing for good starting is to rebuild your starter motor, new brushes and a ball bearing at the brush end works wonders
This is the cheap one, says its for CB900F but fit the R,
Keith
https://www.ebay.co.uk/itm/Powerline-YB14L-A2-AGM-Battery-Honda-CB900F-Boldr-79-83-900-cc/362552600099?ssPageName=STRK%3AMEBIDX%3AIT&
_trksid=p2057872.m2749.l2649