Right now, people would argue that auctions are going crazy. Most of the auctions are going for over 20 HNS each, and a lot of them are going to the hundreds or to the thousands! To profit from HNS, you'd need more HNS to be burned from auctions every day than it is mined. To profit from TLDs, you'd need more HNS to be mined than it is burned from auctions.
Looking at shakestats, we can see that a total of 147,503 HNS was burned last week. With the block reward being 2,000 HNS, that's 2,016,000 HNS mined in a week if the average block time is 10 minutes. That means the majority of the HNS mined isn't being put in auctions, so HNS is more likely to go down in the short/mid-term unless outside factors such as hype play a role, as miners are stockpiling enough HNS to be able to dump the price at any moment.
This means that it's smarter to invest in TLDs than HNS, but you'll need to be picky with what you choose for TLDs. For instance, there can be about 3500^2 emoji pairs, so at the current prices they sell, any emoji pair isn't worth 30-100+ HNS in the long term. You need to include how rare a pair is in the equation too.
For example, categorized emoji pairs are rarer than non-categorized emoji pairs; categories don't grow as much every Unicode update as the whole emoji list. Similarly, twins and singles are super rare comparing to any emoji pairs. Normal emojis are rarer than ZWJ as ZWJ emojis usually come in a lot of variation and are easier to update than normal emojis. Right now, there only exists about 3500 emojis - so naturally, they're worth more than the emoji pairs which have about 3500^2 combinations. Personally, I have some animal combinations, which are in my eyes more valued than just random pairs as they are in the same category, and there aren't many "major" animals discovered that will generate new emojis.
Right now, I would say that investing in TLDs is simply better than investing in HNS. Take that with a grain of salt though, as the specific TLDs can be hard to figure out which are worth investing in with the current prices. Remember to extrapolate the combinations to the max coin supply, and think again if it's actually worth those prices. Also, keep in mind that I'm not calling emoji pairs worthless, but perhaps doing some extra research on the pairs you buy isn't that stupid :)