I have a couple of the Unimat SL1000's and another model I can't think of right now, but I think the Sherline overall is a better quality machine that holds a better tolerance, and is designed with a fairly decent robustness despite the small size, at least IMHO anyway.
I started out in CNC with a Sable-2015, a quite small but exceptionally well made machine that performed quite well, albeit slowly with a reduced DOC, I still have it and bought the high speed precision DC spindle from LukeChan (really well made spindle, recommend it highly!), I still use this machine for PCB work as it holds tolerances really well, and for the light engraving it just excels.
I couldn't have had it more than a month before I realised I made a mistake and should have gone bigger, so I bought a Chinese 6040 which was pretty much all I could afford. Luckily I got the model with the fully supported rails and the 800w spindle/VFD combo instead the crappy DC brushed motor that was more common on these machines. I'd learnt that much early on!
But that then started me down the rabbit hole of failing to get the infamous "blue box controller" with the rubbish TB6560 drivers to work, that was an absolute nightmare until I learnt enough that the actual design itself was completely flawed, and could never actually work (they were shoddy unworkable copies of the genuine YOUCNC drivers). I ended up buying a Gecko G540 for it (they seriously rock and are worth EVERY cent!), and finally had it performing beautifully, I would highly recommend the same machine, but always advise to plan for a Gecko with it if you actually want it to work.
After doing much bigger stuff on the 6040, I was well and truly hooked on CNC, and pretty much immediately realised I wasn't going to be happy long term with the 6040. The things you don't realise before buying are the immense scope of what you can do once you start in CNC, whole new worlds open up, so I straight away started planning for my next tax refund (as this was still very much just a serious hobby) to buy a bigger machine. I'd also got into milling around then and started to fully appreciate the extreme importance of power, rigidity and mass. So I spent ages going through several Chinese dealers direct, and as the Aussie dollar was really great at the time against the USD, imported a 6090, not the desktop one though, the big 350kg beast with large spindle/VFD, really nice linear rails and bearing trucks instead of the round supported rails. Cosmetically some of the work was inferior, but structurally and mechanically it was, and still is a superb machine that runs today as good as it did when I got it many years ago.
I've tried over the years to get the kids involved in creative activities, so have picked up a couple 3040's (great little machines), along with a couple home made 6040 type equivalents I'll eventually Frankenstein into a more solid purpose built machine.
And yes, making pens with the kids is such a joy (I love giving pens to friends, everyone likes a nice pen!), with my two youngest I helped guide them while they designed and machined a pen box, with a poem and dragonflies engraved on the lid, and engraved a message they'd written on the inside, along with a little embedded gold picture frame of them, and they of course made the 3 pens that went into this Mothers Day gift.
I think out of all the things their mum has gotten over the years, she treasures that one the most! Boy she was a blubbering mess when she opened it, and the satisfaction and pride the kids got out of it doing it mostly themselves was priceless!