Generally, the right server will depend on how much you are willing to spend. The more money you spend, the better quality you are going to get. The first thing you will have to decide on is whether you will take a Seedbox with 1 Gbps, 100 Mbps Or 10 GBPS. The amount of speed will depend on your online activity. If you are very active and a constant downloader, there is no use in buying an account that will run at 100Mbps. To reach higher speeds, you will have o download torrents with multiple peers and one torrent. If you download files at larger speeds where multiple people are seeding, you will not get a chance to upload too much. For most servers, larger speeds are common on downloads. 10Gbps accounts will work well if you are a constant user. You will find this very convenient if you are an uploader or you are able to find freshly uploaded torrents.
The server you get will also depend on the kind of tracker you are on. Some trackers will work poorly with 100Mbps because most of their users have larger accounts. When you have chosen the right account for you, the next convenient thing to do is find the right kind of offer. The most important factor to consider when looking into the speed is how many people will be sharing the HDD with you. Find accounts with minimal users on the disk. You should only consider this is you cannot afford a personal one. In case you are getting a one-person Seedbox, getting a 1Gbps can be a convenient speed. When the whole thing is at your disposal, you can use the connection and get the same speed anytime you feel like. Shared servers come in different prices depending on the speed and the number of people seeding.