Ok..............
I totally understand not wanting to deal with petrol/2-stroke machines, they can be extremely frsutrating. Most of that comes down to improper storage over the cool season, the fuel gumming up in the fuel lines and carby from lack of use. This is easy to deal with, simply drain and run the engine till it dies to remove the fuel from the lines. You machine will then start correctly in the spring.
I say all of that because, depending on how much space you are dealing with, petrol is still a viable option for the increased stamina, range and ultimate grunt. (I'm talking the line trimmer here).
Don't mess about, get a Stihl FS38 or FS45 (bent shaft) or the FS 55 (straight shaft). The FS38 should be all you need for about $220. Don't bother with the FS45 C-E, this is the assisted spring starter that is just something to go wrong, ask me how I know this, and most guys are strong enough to start a small 2-stroke without the spring assistance.
https://www.stihl.com.au/STIHL-Produ...584/FS-38.aspx
https://www.stihl.com.au/STIHL-Produ...584/FS-45.aspx
https://www.stihl.com.au/STIHL-Produ...S-55-RC-E.aspx
If you want to stay with the Ryobi battery system, just make sure you have enough battery capacity to get through the job without having to wait for a recharge. I like this one as it looks to be more ergonomic than the cheaper versions, much more like a traditional brushcutter/trimmer -
https://www.bunnings.com.au/ryobi-18...-only_p0396290
For the mower, this is going to be a harder decision. First a couple of basics warnings/recommendations -
-Do not buy an American-style mower. These usually have compromised catching ability by having a small discharge chute and a bar blade. This hampers catching ability. Think Toro, the cheaper Honda's and the variety of spaceship looking battery electric machines.
-Overall, avoid models fitted with a single piece bar blade. In addition to them being fitted to US mowers, they are usually fitted to entry level lawn mowers as they are cheaper for the manufacturers to make. These blades will compromise the crankshaft if you accidentally hit something. They also compromise the catching ability.
-Brands to consider looking at closely include mid-spec Victa, Masport and Bushranger mowers.
Mower Recommendations -
Because you have Buffallo, this tends to soak up more power than say fescue. It's thick and spongy and you really need to have the engine to handle that. Restarting a bogged down engine gets old real quick.
That may mean looking at a good used mower, plenty of which pop up on Facebook Marketplace, although I completely understand if dealing on the platform is not your thing, it's certainly not for me! In this case, look at something like a Victa, Masport or Rover with a 190cc Briggs and Stratton engine. Although these are their older style engine, these have plenty of torque for the job.
I'm not sure what you budget can afford, but I would say buy the biggest engine you can. Most mowers these days sit anywhere between 125 - 140cc. I would say aim for at least the 150cc Briggs, ideally the 163cc Briggs, or if you can reach that little bit higher, the 190cc Briggs. For Victa's, DO NOT buy their V-Series powered models, these have cheap and nasty Chinese motors on them.
Some to consider, I have highlighted the value picks in red as these offer more engine for the money -
Mid Level -
Victa Power Mulcher 163cc $800 -
https://www.bunnings.com.au/victa-po...mower_p0080735
Victa Corvette (625EXi) 150cc $699
https://www.victa.com/au/en_au/produ...00-625exi.html
Victa Corvette 300 (675EXi) 163cc $799 -
https://www.victa.com/au/en_au/produ...vette-300.html
Masport 2000ST DOV 161cc $709 - (This engine is stronger than the 163cc above)
https://masport.com.au/outdoor-garde...sident-2000-st
Higer End -
Masport 4000ST 190cc $879 (Great engine!)
https://masport.com.au/outdoor-garde...0-st-s19-combo
Victa Easy Walker 163cc (Self propelled) $950
https://www.bunnings.com.au/victa-ea...mower_p0080736
Victa Mustang (725EXi) 163cc $999 (Alloy chassis) -
https://www.victa.com/au/en_au/produ...ng-725exi.html
More than happy to help further if needed.