Not what I'm saying. I'm saying, what products have been released under his watch that are just terrible? Apple is a far larger company ever since he took over. He is responsible for apple literally being the biggest company in the world. So I'm really curious what products you think are terrible, since the market obviously disagrees with you?
products that are worse now under his leadership?
MacBook Pro's - These have numerous issues. weak hinges, terrible keyboards, thermal throttling due to poor cooling.
Products with no improvements or major changes under his leadership: Mac Pro, iMac, MacBook
Products killed under his leaderhip - AirPort, Apple Display
Products that were actually ok under his leadership: The Watch
for the most part the rest of the products have been very hohumm with cook in charge. Directionless in design, driven by cost analysis.

but that's just one that's outright terrible. for the most part, the products aren't terrible. They're quite good. But they're not 40% more "Good" than the competition. My issue with Tim isn't necesarily the product outcome, but the business ethics and his intention.
Also: APple is not the biggest company in the world

just as an FYI, thats a misnomer. Apple had the larges Market Capitalization for a Publicly Traded company in the world. There are a lot of companies larger by assets, and employees. There are even a few companies on paper who are bigger monetarily, but do not publicly trade (think Oil)
the market doesn't necessarily disagree with them either. While we have a short term trend at best, there's alreay the start of a trend that Apple users aren't returning for future purchases.
Last quarter, Apple's Mac Sales were the lowest in volume since 2010. the iPhone sold 9 million less units in the quarter as well. We will need to see if Apple's done something to reverse that in the months that have just past. But the question on the table is, since last quarter, has Apple done anything significant yet to move that needle? Are the iPad refreshes going to suddenly bolster where 9m iPhones and 1.5m less Macs were in decline? What about the Credit card? Is this going to offset enough? these are important questions that Tim has to navigate. In previous year, when he expected lower volumes, his reaction was "raise prices" to keep the financials up. This indicates his primary motivation in business of running Apple is appeasement to the Stock Market, in order to keep market cap high despite falling numbers.
That's never a good look for a business. Keeping market cap and profits high while volumes decrease for businesses typically end up with cost cutting measures that further affect the quality of the product. We're already seeing quality declines in the MacBook Pros because of this (the hinge defect that popped up is a direct result of a cheaply implemented hinge cable). if users continue to bleed away due to high prices with products that don't differntiate themselves high enough to be worthy of those premium prices, it will evntually show in the numbers. You'll almost never see an overnigth 100 to 0 customer drop off. But death by a thousand cuts.
Apple has typically never done well long term under the leadership of accountants and sales people. The culture of it, with claiming of products that "just work" and showcase technology in user friendly, but fashionable devices requires someone who understands those concepts and user behaviour. Tim Cook doesn't understand the user. Jobs always did well because he knew what users ultimately wanted and demanded that the products meet that. Then priced them accordingly. (even if he was a douche

)
Tim Cook is the guy you want as your CFO or supply guy. To tell you HOW to maximize your profits on products you've already designed. But as head of the company where he's responsible as well for final say on products, he's been woefully inadequate.
who's a suitable replacement? **** if I know. there's 7 billion people on this planet. Start interviewing