These mice are very similar in many aspects however their shape is fairly different. They are both tiny mice and therefore do not cater to those with larger hands very well. The Logitech G203 is the slightly smaller of the two. It is about 4mm shorter and about 5mm thinner. Both mice are roughly 38mm high, however the SteelSeries Rival 3 looks taller due to its bigger curves. Neither mouse is suited for palm grip and, although smaller hands can palm these mice, there are plenty of other options that have much better ergonomics for palm grip. Both mice favour claw and fingertip grip. Those with very large hands may struggle to claw these mice, everyone else should be able to comfortably use both mice with claw and fingertip grips. In my opinion, the flatter shape of the G203 makes it better for fingertip whereas the hump and extra length makes the Rival 3 the better mouse for claw grip.
The Rival 3 is just 77g while the G203 is 85g. Clearly both of these mice are very light, and neither have adjustable weights. If you are buying one of these mice you probably want a mouse to be as light as possible. Therefore, although the 8g difference isn’t huge, picking up both mice you can notice the Rival 3 being lighter so it obviously wins in this category.
Both sensors have very similar specs and felt precise, accurate and were very responsive. The higher lift-off distance on the Rival 3 made it a clear loser in this department, however once I got used to the higher lift-off distance, I no longer experienced much cursor jiggle. The Logitech G203 tracked at a height of 3 playing cards whereas the Rival 3 tracked up to a height of 8 playing cards.
The primary mouse clicks were a strong point in my individual reviews for both mice, so I have no complaints about either. The G203 feels more premium due to its slightly sturdier button however this means the buttons on the SteelSeries Rival 3 can feel lighter. Even this observation is very minor, there is no clear winner here.
Both mice have a total of 6 buttons: the 2 primary mouse clicks, scroll wheel click, DPI changing button (can be reprogrammed) and 2 side buttons on the left-hand side. I would rate the DPI changing buttons equally, both were easy enough to press and were more than adequate for their simple function. The side buttons were not so equal. On both mice the buttons were thin and stuck out a fair bit, making them easy to find. The buttons on the Rival 3 take way too much force to press and even after using the mouse for a while now this still bugs me. The Logitech G203 on the other hand has easy to press buttons which as a result feel much more responsive and were a pleasure to use.
Both scroll wheels have a rubber feel and distinctly scroll between each tick. The only difference is the wheel on the Rival 3 is sunk a bit lower into the body of the mouse, in combination with there not being a gap between the primary mouse clicks, there is not a huge of range of motion. There is more than enough for games, this complaint only has an effect on scrolling webpages and productivity tasks.
Lights and Software
Both mice had a very similar approach to their RGB lights, a large lightbar curving round the back of the mouse and the logo. Both mice have three RGB zones which can be used to create cool lighting effects. The lights were vibrant and good looking on both mice. I personally thought they were a little brighter on the Rival 3 with slightly better colours.
Everything is controlled through the Logitech G Hub Software and SteelSeries Engine respectively. Both were easy to use a and offered a wide range of features. As well as the ability to sync up any other products you have from one of these brands. You can watch the individual review of the mice for more information. Both pieces of software allowed easy changing of sensitivity, lighting and buttons with multiple profiles and fine-tuning options. Neither software was better in my opinion.
In this verdict I want to give a clear answer of which mouse is better for each person. Starting with fingertip grip, I feel the shape of the G203 suits fingertip a little bit better. In addition to this the lower lift-off distance and easy to press side buttons make it a winner. It is suitable for all hand sizes with fingertip grip.
If you use claw grip, then it is a bit of a harder decision. Obviously, the sensor and side buttons are a plus for the G203. I am a claw grip user and I prefer the shape and slightly lower weight of the SteelSeries Rival 3 making it the mouse I would choose. If you have large and particularly very large hands and are a claw user, I would suggest not buying either of these mice.
Palm users should really look at other options. Those with small hands may be able to use them both with decent comfort. If you are a palm user and want one of these two mice, then I think the G203 is the better of the two. However, there are plenty of other budget mice which are much better suited for palm grip.