If you like Texels, they have the advantage that they're easy to sell, easy to get tups and so on. The only real disadvantages are that you can get some difficult lambings, and they don't always have the best of feet.
You can avoid the worst of the lambing problems by tup choice and by culling any ewe that needed assistance. In choosing a tup, personally I have found that head size isn't relevant, the most important measure is narrow shoulders, and you don't want too exaggerated a rear end. Another approach is to use a different breed of tup - Beltex X Charollais gives great lambs and easier lambings, but won't necessarily improve feet. A Shetland tup will give you easy lambings, great feet, ewe lambs that are good in your flock (and themselves give easier lambings and better feet) and fat lambs that are very saleable - but won't fetch quite as much as pure Texel would have, and will take a little longer to grow. (However, you'll probably rear more of the Shetland X lambs than you would pure Texel...
). Another type of tup you could try is Cheviot; great feet, usually, lambs born small and grow steadily off grass. You get fabulous fat lambs but a lot later than you would with pure Texel, so you'd need to be happy to keep some of them over winter - but then the prices are usually very good in spring. And you could keep some of the nice ewe lambs in your flock - although you wouldn't tup them as hoggs.
I don't think there could be much doubt that of the breeds you mention, Lleyns would be the easiest for a beginner. They rarely have lambing problems, their feet should be good on the whole, the fat lambs will sell just fine (though won't fetch what good Texel lambs would - but again, you'll probably rear more lambs per ewe with Lleyns.)
Some strains of Lleyn are very prone to triplets and even quads, so I'd try to avoid those strains, especially if you don't have lots of really good grass. (A Lleyn ewe can rear triplets on good grass, but any ewe would struggle with three lambs on land like we have!)
The thing about foot trimming is that the best approach is to breed sheep with good feet. And if your sheep have less than great feet, it's incredibly easy to make things worse by trimming, even if you trim well, so the generic advice is to trim as little as possible.
And having said all of that, if your requirement is sheep that are easy to care for, docile, easy lambing, for your freezer - well, you'll go a very long way to improve on the Shetland. Taste in a different league to Texels or other commercial breeds. Need to be tamed, but if you buy from a hand-tame flock, you should have no trouble with that. And they're so pretty!
And you can take up spinning with with their gorgeous fleeces...
Soay can also be very tame, have superb feet and easy lambings, and taste wonderful. They're even smaller than Shetlands though, and butchers generally charge per animal, so the smaller your sheep, the more per kilo the butchery costs. (My butcher charges £24 per animal, including slaughter fee. I get about 14 kgs off a well-grown Sheltand hogget, or a few kilos more if I give them two summers. A Texel lamb would give you 20kgs or more at the end of one summer.)
And, so that you can calibrate my input, I've farmed full-time for 10 years; three with Swaledales, Mules and Texel and Beltex lambs out of Mules (some of which lambs we put in our own freezer) - about 800 lambs per year from all, on moorland; seven years with a 250-head commercial Texel-type flock, with some Mules, on disadvantaged upland ground, using Texel, Charollais, Beltex, Dutch Texel and Sheltand tups, and with my own flock of fleece sheep for the last 4 years, now at 35 head of mostly Shetland crosses. All lambing outdoors in the north of England, apart from the 80-head Mule flock on the moorland, which we lambed indoors a little earlier.
We've had a batch of Cheviot store lambs to winter, and have had Cheviot X Texel ewes in the flock; we've tried Lleyns (and I worked on a farm previously which had a 70-head flock of Lleyns.).
Oh, and I've eaten Zwartbles and I must say it tasted very nearly as wonderful as Shetland, Manx or Castlemilk Moorit. If you have a large family and want big joints... (But from Womble's experience, plus other Zwartbles flocks I know, you will probably need to Footvax and cull for bad feet after footvaxing.)