I have a fundamental question to the Bioinformatics community in general.
Two different sequencing platforms produce sequencing reads prepared in the same way by the same protocol that has to be matched with a reference genome/transcriptome. one of them is of the length 70 bps and the other one is around 150bps. How do you know whether one alignment is more accurate than the other?
Any information regarding the query will be useful.
For common experiments, the difference between both of these will be negligible, i.e., not noticeable. You would have to sequence the [c]DNA to an extremely high depth of coverage to be able to have the statistical power to detect differences between both, in which case it can be inferred that 150bp would result in more accurate alignment of reads.
However, ultimately, as it can be assumed that you are referring to Next Generation Sequencing, both read lengths --and the informatics tools used to process these-- would be terrible at faithfully representing the [c]DNA sequence that they are supposed to decode.