Over on Minor League Ball, John Sickels has published two very preliminary top 50 prospect lists for next year:

Hitters

Pitchers

There are seven Mariners in all, headed by Mike Zunino and Taijuan Walker:

• 7P Taijuan Walker
• 17P) Danny Hultzen
• 25P) James Paxton
• 44P) Victor Sanchez
• 8H) Mike Zunino
• 16H) Nick Franklin
• 25H) Brad Miller

Also mentioned in comments is that Brandon Maurer would be somewhere in the 51-60 range amongst pitchers, and given previous comments that Sickels has made I'd guess Stefan Romero would be somewhere similar amongst hitters. Given Sickels' typical grade ranges this would give us a top 9 something like:

Taijuan Walker A-

Mike Zunino A-

Nick Franklin B+

Danny Hultzen B+

Brad Miller B+

James Paxton B+

Victor Sanchez B

Stefan Romero B

Brandon Maurer B

Miller and Paxton would be somewhere near the B/B+ border, so either or both might be a B. Not sure who would round out the top 10 - I'd go for Morban if his best position didn't seem to be DL.