My thoughts:
Spurs vs. Dnipro - not a terribly hard match, but not one to take lightly, either. On paper, I favour Spurs, but the game ain't played on paper!
Betis vs. Rubin - if both teams play their best football this will be
very close. That said, Betis is dead last in La Liga while Rubin is lower-mid-table in Russia, so I wouldn't necessarily count a Rubin win as an upset.
Swansea vs. Napoli - The Serie A may be a slightly weaker league than the Prems, but unless Swansea ups their game, Napoli have this one.
Juventus vs. Trabzonspor - going on current form, Juve should have this easily. Trabzonspor, who are usually the best non-Istanbul side in Turkey, are not playing up to their usual standard, plus Juve have lost just once in Serie A this season.
NK Maribor vs. Sevilla - one word. LOPSIDED. Maribor will have to pull off a miracle to win this. Yes, they beat Wigan. Wigan is mid-table in the Championship this season, which is indicative of their form. Yes, they beat Zulte-Waregem. So flipping
what? Sevilla, who are 7th in Spain right now, are a superior opponent to both sides.
Viktoria vs. Shakhtar - I favour Shakhtar in this one, but Viktoria aren't as far removed from them as Maribor is from Sevilla, so they may be able to pull something off.
Chornomorets vs. Lyon - With Lyon's sub-par league form, who knows? Chornomorets are even with Dnipro in points in the Premyer Liha and facing a team with worse form than Spurs, so they have a better chance of pulling this off IMO. Still, Lyon can't be written off.
Lazio vs. Ludogorets - Ludogorets won a weak group and Lazio finished behind a league-lagging Trabzonspor. Who knows how this is gonna turn out. To be blunt though, I hope Lazio loses, if only to stick it to their eejit fans.
Esbjerg vs. Fiorentina - Esbjerg are in the red zone of the Danish Superligaen, which is not the strongest of leagues to begin with. Fiorentina are fourth in a respectable league. Upsets happen, but I honestly think the Gigliati have this one. And so much the better - I happen to like Fiorentina.
Ajax vs. Salzburg - Ajax has the name, Salzburg has the smokin'-hot form. This match should be a classic. I'd pick Ajax to take this simply because they didn't miss the Champs League knockout stage by that much.
Maccabi Tel-Aviv vs. Basel - Basel weren't horrendous in CL, but they weren't great, either. Maccabi have something to prove. Although I still favour the Swiss side, it will be close. And Basel need to take the warning from Eintracht - Maccabi beat the top team in their group, so they do have a shot at beating Basel as well.
Porto vs. Eintracht - speaking of Eintracht Frankfurt, they have the lucky loser from a
very close CL group, so they can't derp the match up like they did against Maccabi if they want to win this. To their credit, they have the ability to get goals from a number of sources. On the downside, their league form has been deplorable and they are barely outside the red zone.
Anzhi vs. Genk - So you have a second-place team that won only against sub-par opposition and got smoked by the first-place team's A-team, against a first-place team that couldn't beat the team that finished third in their group. But the latter, Genk, has much better league form going for them right now - they are fifth, while Anzhi is dead last. I'd tentatively pick the Belgians to take this one.
Dynamo Kyiv vs. Valencia - Valencia may have lost their opener to Swansea, but they bounced back and didn't lose for the remainder of the group stage, finishing top in one of the tougher groups. Dynamo wasn't bad, but Genk had their number, and I rate Valencia more than Genk in spite of the former's lagging league record this season.
PAOK vs. Benfica - Benfica must see red, figuratively, when they see any team from the blue and white, literally, because of the fact they lost to Olympiakos on goal differential in a group rivalled only by one other in the Champs League for its closeness. If they can't beat the best team in Greece, maybe they can beat the second-best, whose Europa League record was decent but against weaker opposition. Either way, this is gonna be fun to watch, if nothing else. I favour Benfica, but only slightly.
Slovan vs. AZ - if one were looking purely at league form one would think AZ had this one even though the two are about the same in their respective leagues. But consider also that Slovan could not be beat by Sevilla, a team I rate higher than these two both with good reason. Honestly, this could go either way.