Although I am still a fairly inexperienced mouse breeder and I only breed dove selfs at this stage, I have bred a few different rat varieties (mostly marked) and I just thought I'd post my two-pence worth about the "easy beginner varieties" vs "difficult varieties" debate. A few people have recently come on the forum and asked for recommendations for a good beginner variety so I've been thinking about this quite a bit.
I have come to the conclusion that there is no such thing as an easy beginner variety. The pink eyed selfs, c-locus mice, tans etc, although it's easy to find really good starting stock, it only takes a couple of bad decisions and they're ruined and you have generations of work ahead of you to put it right. Every variety has it's easy and difficult points and I reckon they all balance out at the end.
For the pink eyed selfs you have tan vents, type, an even top colour of exactly the right shade, thick smooth belly fur with no lines, amongst other things. You are competing against some incredible mice bred by long-standing incredible breeders and your self mice really do have to be the absolute best they can be.
With the dark selfs, you have to take in to account the things for pink eyed selfs with the addition of making sure the toes and tail are fully coloured, there are no stray white hairs - but with blacks in particular you have the trade-off that they're not expected to be quite as big and typey as the pink eyed selfs.
With the c-locus selfs, namely PEW and BEC, although you can find fantastic starting stock very easily and you don't have to worry about tan hairs etc, but you are again competing against other mice with amazing type, colour, etc and the most teensy minor fault could put you down to the bottom of the class.
For the agouti-based mice, you have all the same concerns with the added fact that the two or more colours on each hair have to be the right shade, the right amount, and that the ticking is the right colour and evenly distributed. This is balanced by the fact that they don't seem to be as popular in shows and therefore (potentially) it would be easier to win an agouti/cinnamon class than a champagne class (for example) - but you've still got to compete for BIS.
For the tans, you've got to keep in mind the top colour, type, throat spot, tan spreading too far and not being bright enough, but it is fairly easy to find good starting stock.
Shaded mice are prone to awful-looking moult lines and, according to the law of sod, these are guaranteed to show up the day before a show. Early selection is also difficult as points don't develop until at least six weeks. On top of this you still have considerations for type, overall colour etc etc.
With the marked varieties, you have to keep/breed a LOT more mice and they are more difficult than the selfs in that it takes more work to look after a larger number of mice - but I know from breeding marked rats that it is mostly down to luck with some selective breeding involved when that perfectly marked mouse wins everything for months on end.
This is all just my opinion of course, and what I have gathered from my own breeding of pink eyed self mice and various varieties of fancy rat. With my self mice, I have lots of difficult decisions with the breeding - things like "do I breed that perfectly coloured and typey dove doe with the raging tan vents to Heather's stunning silver buck with the clean vents? Will I end up with doves that are too pale but no tan, or will the tan carry through, or will I end up with something in the middle? Or instead do I breed that too dark dove doe with very little tan round the vents but poorer type to the same huge silver buck? Will that breeding result in offspring with poor type, or will the buck's type carry through? There won't be any tan to worry about though and the top colour should come out right..." So no, pink eyed selfs are not easy by any stretch of the imagination.
I believe the absolute most important thing when choosing a variety to show is whether or not you can look at 30+ mice, all with the same colour/markings, day in day out, year after year. You have to be focused on making your chosen variety the absolute best it can be, which takes patience, persistance and passion over years. Breeding randoms, too many varieties, or moving from one variety to another every few months will not bring success on the show bench in the long run.
So basically, what I'm saying is that if you are really passionate about Dutch mice, astrex, reds etc etc and you truely believe they are the most beautiful of all mouse varieties, then go for it. Choosing a variety you like less to start with because you've been told they're easier will not do you any good when you're cleaning your mice out, examining them, pairing them up, and the whole time you're thinking "I wish these were Dutch rather than Ivories."
ETA: Ohmigod, I've just seen how long this post is! Sorry