Also a previous border collie owner, have a miniature and 2 standards. Im not an expert but Il give you what my experience is.
I have found poodles generally easier to train, just as bright to my surprise, and get past adolescence around a year younger than border collies which is great.
Standards i think are the better poodle size within the breed, but that's only my opinion.
Shows are usually agility or form/looks generally (but I'm not in the US).
Big focus on general appearance which you should be able to get AKC standards online for, having health tests done for sire and dam, and parents temperament is looked at, but im not an expert breeder with decades of experience.
This forum isn't a bad place to start to ask questions, there is a cheap online poodle book which is downloadable which i got, just google "all poodle info" (absolutely no affiliation with them whatsoever-just found it generally quite good for a broad knowledge).
Suggest you contact your local poodle club for info, just beware of the odd competitive/money hungry club member/breeder giving you misinformation/holding back on info as I have come across a few over time - but the vast majority of poodle people have been ultra helpful and genuine.
Grooming is a big part of their appearance for shows, collies are a different type of dog altogether when it comes to this, I didn't realise the full extent of it, I just thought ya ya long coat, prone to matting ya ya bit of extra work...
Its hard to get a good groomer that can actually do proper show grooming for poodles, you may have to do this yourself. It's expensive too over time, and of course time consuming. Standards take hours and hours and hours to wash, dry, cut and style properly - every time they get wet or dirty you have to sort it out straight away, to avoid mats or staining - this is much easier to do with a miniature or toy, but still a pain. Staining around the mouth and eyes can be a problem with some of them in the lighter colours and must be tended to daily if you want to show at any time. You can't just leave them in between shows and sort it out later as the coat won't get to a good enough length in between shows if you have to cut it. If you intend to show from puppy, when the puppy coat starts shedding you have to be extra careful, tangles can appear overnight, this goes on until they are about 2. Brushing isn't like with another hairy dog, if you have to leave length on the coat for showing, its far more tedious you can't miss anything, right down to the root. If you aren't going to show, you can keep a short pet clip and they are no worse than most other dogs with any length - its the showing grooming that's hard. Bit less work with black or red or other non light colours.When they say the grooming is extra work it is, even if you use a groomer, its got to be kept on top of every day. They are worth it though, they are stunning groomed.
With breeding/selecting mates/buying a puppy, have to be very careful with the fur to eye/nose colours, with fading and mixing. Can't breed x colour with x colour or the parent colour can be lost (fade later on), or you end up with the wrong eyes/mouth/nose for the hair colour which wont conform to show standards either. Even though its not allowed, some people dye white mismarks on the dogs then show and breed them, hence why so many have mismarks still, generally solid colours and only fading on a couple of colours is show standard. They are ideals, depends how far you want to go with the shows, some of these things are overlooked at times depending on how bad the fault is, and depending on the show.
Agility - i find the miniature a lot more bouncy and abnormally agile, know of toys being good also, standards agile for size, probably best if you want agility to go with a line of agility successful sire/dam where the breeder can advise you along the way.
Poodles are a fairly consistent breed with their trainability and good nature, they're a pretty safe bet, they have a few health issues, just get screened parents/lineage to be safe for the big things, other small things like ear infections is a floppy ear dog thing and is manageable.
Definitely wouldn't recommend having poodles not in a pet household situation, ideally if people are coming and going, not too many long periods fully alone, even though they are affectionate I found collies a bit more independent, less bothered about being left alone and that type of thing.
Hope some of the info may be of use to you.
. As was said, some breed more for dogs who hunt, but you'll find conformation dogs there, too. With Poodles, as our member Tiny Poodles says, conforming to the standard creates a healthy, functional Poodles (hopefully not misquoting her). You can locate the standard at the PCA website.
