I haven't tested powerpoint on either Kingsoft or OfficeSuite Pro, but I'd have to say hands-down Kingsoft wins, despite OSP's $15 price tag. The interface is also very reminiscent of MS Office. There may be features missing in KS but present in OS, but I haven't encountered any situations where I needed them or noticed the absence
Kingsoft is waaaayy more feature-rich, compared to OfficeSuite. I'll do a feature comparison below:
Word docs
OfficeSuite Pro: save, undo, redo. basic formatting--font size, color, cell bg. Paragraph alignment. Bullet-points, numerical or bullets. Can add font styles/change font type, but it's a little cumbersome. Print.
^Much more screen real estate because there's no options bar on top. Though, many features are hidden away and cumbersome to access (e.g., not as easy to go to 'view' mode whereas on KS it's just a one-button click).
Kingsoft: Copy, paste, undo, redo, find, spellcheck, insert, font formatting (same as OS), paragraph formatting. Style. Comments and revise. Bookmark. Change layout. Zoom. Wordcount. Share (evernote/email). Encrypt. Page setup. Reading setting. Switch to 'reader' (removes formatting options). Print.
^Layout is very similar to Word--bar on top with symbols grouped by type--click on one to expand (e.g., clicking 'font' expands to various font customizations). Nice bc everything is just on top, you don't have to go to another screen to format. VERY intuitive, easy to access features. Straightforward.
Spreadsheets
OfficeSuite Pro: basic formatting--font size, style, color, cell bg, alignment. Auto-sum. Turn a cell into $ or %. A-Z sort. Chart insertion. Print
Kingsoft Office: all the above, much easier to access. cell merge/delete/insert/fill. borders. filter/sorting options. comment. hide headers. encrypt. protect. print.
^again, VERY visual and easy to view access basic formatting
The ONE feature that does seem to be lacking with Kingsoft is that it doesn't automatically upload your doc back to the cloud. With OfficeSuite, I can access/edit/save something directly from my Box account. With Kingsoft, I can grab something from the web, but I have to save it to my tablet, then back out and do a separate, more time-consuming 'send cloud'.
My advice--before you go ahead and buy one, test out a free one like Kingsoft. If you feel it's lacking features that you absolutely need--that paid apps would provide--go for it. But the bottom line for me is, features are SO much easier to access with KS, and it's much more intuitive. Again, very Word-reminiscent. With OSP, features are hidden away between different options, which is cumbersome but does expand screen real estate. Hope that helps!