This is my take on the final 3...
Arie, while they share a similar thread (racing) and Emily feels comfortable there, like Arie's mom said, her husband is gone most of the time. I don't think that is what Emily is looking for. She wants someone who can step in and be a dad to Rickie and a husband and a father to future kids....racing will impeade that. (i dated a racecare driver and racing always came 1st as it was bread and butter, but it meant long weekends away).
Sean, he has the stability of someone who can be there more often (home nights ans weekends) but how much, as an insurance salesman can he make? It seems as if Emily likes the finer things (her house is huge for 2 ppl, she is dressed nicely, grated that is provided by the show, and she is a SAHM who basically lives off of Ricky's parents..jsut assumign there, but how else could she not work and be a soccer mom?) I just don't see them working out as he doesn't seem to have a disposable income.
Jef, has money and stability. He seems young at heart, but is always thinking of Rickie (the puppet doll he went back for) and I think Emily notices that. He has the income that Sean doesn't, the nice family that Arie doesn't.
That's my 0.02!
I also think Emily wants a hubby who will be around. She already raised one child alone and that was a lot, with or without being healthily financed. I can see her really resenting her hubby being away while she's got 4-5 kids she's basically raising alone. She also doesn't want a wimp for a DH. Arie seems wimpy.
I know she told Arie that his being away is okay, because she likes being alone a lot & she's used to it. But, that's the kind of rationalization one says when they are
trying to make things okay with someone they really like. Don't ask how I know.

Other times she's talked, it doesn't seem she wants to be alone
thatmuch. She even asked his mom about it, it was such a concern. Then tried to make it okay, since the mom had made it work.
I also don't see her uprooting 4-5 kids every weekend just to travel with Arie.
I think Jef would be perfect for her
3 years from now. But, Emily's made it clear that she really doesn't want Rikki to be so old age-wise that she won't be close to her siblings. She wants to start a family as soon as all the dust settles and everyone, especially Rikki, is adjusted to it all. that means Rikki could be 7 or 8 when her first sibling is born. And 9 or 10 when another is born.
While I thought it was great to see Sean & his dad playing those jokes on Emily and obviously hamming it up for the camera. They obviously knew this was a "typical" bringing the GF home to meet the parents. A PP from TX said something along the lines, of I know his type and WHY he is still available to this day. It started making me wonder, just how MANY of these practical jokes does Sean do in a day? And is it just all in fun, or is there a streak of emotional immaturity in him? A couple jokes here and there, she can be a good sport about. But, will Emily, one day be saying, "Will you just grow up? Enough with the jokes already! I didn't know I'd have another kid, with all the joking and insensitivity to my feelings & how uncomfortable they make me?"
It's a toss up right now, which guy she will pick. But, I don't think
any of the three are really fully right for her.